The cathode ray tube monitor is the traditional display device for the personal computer. Flat display devices, such as LCD monitors, offer several advantages over CRT monitors because they emit less radiation, consume less power and take up less space. As technology advances and prices of display devices fall, flat display devices are replacing traditional CRT monitors. However, updating the monitor comes with an annoying problem—the re-configuration of the video signal.
FIG. 5 is a flowchart illustrating the well-known displaying process between a computer host and a display device. In step 502, the host outputs a video signal to the display device. Typically, each display device has its own acceptable signal attribute specification, such as horizontal frequency, vertical frequency, resolution and the like. When the display device receives the video signal, it determines whether the video signal is acceptable or not (step 504). When the video signal is in line with acceptable specification, the video signal is properly displayed (step 506). When the video signal is outside the range of the acceptable specification, however, the display device responds by displaying an error message to prompt the user to re-configure the attributes of the video signal.
This circumstance usually occurs when the user replaces the old monitor with a new one that does not support the original configuration. For example, a user installs a new monitor that supports a maximum frequency of 75 Hz while the original configuration of video signal frequency is at 85 Hz. When the display device cannot handle the video signal, a traditional monitor simply leaves an error message on the screen, such as “Out of range.” The system cannot take any steps, such as automatic re-configuration, to solve the problem. Indeed, user intervention, such as rebooting or manual re-configuration, is required before the display device can properly display the video signal.
The traditional process is complicated, time-consuming, and not user-friendly. Moreover, it requires additional knowledge and skills on the user's part to complete the manual re-configuration process. Therefore, there exists a demand for an adjusting method for automatically detecting the attribute specification of a display device and automatically modifying the attributes of the video signal.